Electronic components such as a power transistor and an IC package, which are mounted on a printed circuit board (PCB) generate heat during operation thereof. Thus, a heat sink for releasing heat from the electronic component is often provided on the electronic component. The size of the heat sink is selected in accordance with a cooling capacity suitable for an amount of heat generation from the electronic components. Accordingly, the heat sink may be bigger than the electronic component as necessary.
Heat sinks are in tight contact on heat-generating electronic components to achieve a good heat-releasing effect. For example, JP-A-4-186752 and JP-A-2000-22059 disclose a method of mounting a heat sink to an electronic component in which a heat sink is placed on an electronic component. The heat sink provided on the electronic component is further secured to a mother board with a screw or a clip, or by stretching a wire. However, a screw hole or a clip insertion hole, or an anchoring member for stretching the wire is to be provided on the printed circuit board, which results in reduction of the mounting space for electronic components on the printed circuit board. To counter this, JP-A-2007-142294 discloses a method of bonding a heat sink to an electronic component with cement.
On the other hand, electronic components may be removed from the printed circuit board and repaired (or replaced) due to defects. The defective electronic component may be removed from the printed circuit board by locally reflowing solder joint of the defective electronic component. However, in a case that a heat sink is provided on the defective electronic component, the heat from the reflow is released through the heat sink, thereby making it difficult to melt solder joint of the target electronic component.
To counter this, the above-mentioned JP-A-2007-142294 discloses the heat sink device having a heating element and the heat sink which are bonded via the cement. A threaded through-hole for separation is formed in the upper part of the heat sink for separating the heat sink from the heating element, and a separation jig is provided which screws into the threaded hole for separation.
However, when the heat sink and the heating element are strongly bonded with each other, a powerful force has to be applied to the bonding surface of the heat sink for separation. According to JP-A-2007-142294, the heat sink is vertically separated from the heating element. Thus, the heating element may be damaged. That is, in case of using strong cement, an excessive mechanical stress has to be applied to the electronic component, which may break the electronic component.